The present invention relates to a coated polymeric fabric.
Polymers are used extensively to make a variety of products which include blown and cast films, extruded sheets, injection molded articles, foams, blow molded articles, extruded pipe, monofilaments, and nonwoven webs. Some of such polymers, such as polyolefins, are naturally hydrophobic, and for many uses this property is either a positive attribute or at least not a disadvantage.
There are a number of uses for polymers, however, where their hydrophobic nature either limits their usefulness or requires some effort to modify the surface characteristics of the shaped articles made therefrom. By way of example, polyolefins, such as polyethylene and polypropylene, are used to manufacture polymeric fabrics which are employed in the construction of such disposable absorbent articles as diapers, feminine care products, incontinence products, training pants, wipes, and the like. Such polymeric fabrics often are nonwoven webs prepared by, for example, such processes as meltblowing, coforming, and spunbonding. Frequently, such polymeric fabrics need to be wettable by water. Wettability can be obtained by spraying or otherwise coating (i.e., surface treating or topically treating) the fabric with a surfactant solution during or after its formation, and then drying the web.
Some of the more common topically applied surfactants are nonionic surfactants, such as polyethoxylated octylphenols and condensation products of propylene oxide with propylene glycol, by way of illustration only. These surfactants are effective in rendering normally hydrophobic polymeric fabrics wettable. However, the surfactant is readily removed from the fabric, often after only a single exposure to an aqueous liquid.
Substantial efforts have been directed to increasing the durability of surfactants which are topically applied to a polymeric fabric. Such efforts include the following, by way of illustration:
(1) use of a composition which includes water, a primary surfactant, and a cosurfactant which is functional to wet the fabric with the composition and which provides for substantially uniform distribution of the primary surfactant onto the polymeric fabric;
(2) use of a surfactant, with or without a nonionic cosurfactant, which is the reaction product of an acid anhydride derivative, such as a substituted succinic anhydride, with a polyhydroxy compound, such as sorbitol, a polyethylene glycol, triethanolamine, a polyhydroxyamine, certain primary and secondary amines, and certain unsaturated aliphatic sulfo compounds;
(3) use of a surfactant, with or without a nonionic cosurfactant, which is the reaction product of certain unsaturated aliphatic sulfo compounds with the reaction product of an acid anhydride derivative, such as a substituted succinic anhydride, with a polyamine having at least one NH group capable of addition to a double bond;
(4) use of a surfactant mixture which includes an ester-acid, ester salt, or a mixture thereof, and an amidic-acid, amidic salt, or mixture thereof, with or without a nonionic cosurfactant; and
(5) use of a surfactant mixture which includes a sorbitol succinate surfactant, such as an ethoxylated amino sorbitol succinate salt or an alkenyl succinate anhydride ethoxylated fatty amine salt, and a cowetting aid which can be, for example, a silicone polyether or a primary or secondary alcohol having up to about 8 carbon atoms.
In addition to water wettability, another property of concern for many applications involving shaped articles made from polymers is the tendency of the shaped article to adsorb protein. For example, the adsorption of protein by polymeric fabrics which are employed in the construction of the disposable absorbent articles noted earlier can be a disadvantage. This is particularly true in the case of feminine care and other products which come in contact with blood and other protein-containing body fluids, some of which are colored. The adsorption of protein by a component of the product contributes to disapproval of the product for aesthetic reasons, even though the product may have superior performance in its intended function of fluid absorption and redistribution. More importantly, however, the adsorption of protein often reduces or prevents fluid absorption.
In the past, resistance to the adsorption of protein by a polymeric (or other) material has been accomplished by, for example, the radio frequency glow discharge plasma deposition of tetraethylene glycol dimethyl ether onto a polymeric material; coating of a polymeric material with polyethylene oxide-containing block copolymer surfactants or a polyethoxylated alkylphenol or long-chain aliphatic alcohol, with or without a radio frequency argon glow discharge treatment after the polymeric material has been coated; immobilization of baboon albumin on radio frequency glow discharge-treated surfaces; radio frequency glow discharge polymerization of monomers on the surface of a material; a coating of a crosslinked polypropylene glycol/polyglycidoxy propyl methyl siloxane network which contains polyethylene glycol monomethyl ether chains; use of interpenetrating polymer networks of poly(ethylene oxide) and a polyether substituted polysiloxane; use of poly(dimethylsiloxane)-poly(ethylene oxide)-heparin CBABC type block copolymers; and use of immobilized poly(ethylene glycol) films.
Notwithstanding the advances which have been made in rendering a polymeric fabric wettable and in providing surfaces which are resistant to the adsorption of protein, there still is a need for further improvement in these areas. More particularly, a method is needed by which a polymeric fabric can be durably rendered wettable (or hydrophilic) and resistant to protein adsorption, by applying a surfactant to the fabric from an aqueous medium without the need for a subsequent radiation treatment.